🔍 Key Concepts

• piston ring sealing surface appearance and what different discolorations usually mean • how hot combustion gases leaking past a ring affect its color and surface • difference between normal lubrication patterns and signs of gas blow‑by

💭 Think About

• If the sealing surface has blackened areas, what process in an engine could cause localized burning, carbonization, or staining on that surface? • Would properly seated, well‑lubricated rings typically show uniform, light wear marks or patchy dark burned spots? Why? • Which choice best matches a symptom of gases escaping past the ring instead of sealing correctly?

✅ Before You Answer

• Compare the words "lube oil" vs "hot gases" – which one more commonly leaves burnt, carbonized black marks on metal? • Think about whether rotating rings or gas pressure behind the ring would change color, or just change how the ring moves/seals. • Picture normal vs abnormal ring appearance: in which condition would you expect dark, burned areas exactly on the sealing edge where combustion leaks could occur?